Printing hammer arrangement



Dec. 20, 1966 u'rz 3,292,531

PRINTING HAMMER ARRANGEMENT Filed Nov. 29, 1965 Patented Dec. 20, 19663,292,531 PRINTING HAMMER ARRANGEMENT Gerhard Mutz, Villingen, Germany,assignor to Kienzle Apparate G.m.b.H., Villingen, Black Forest, GermanyFiled Nov. 29, 1965, Ser. No. 510,409 Claims priority, applicationGermany, Nov. 28, 1964, K 54,658 8 Claims. (Cl. 10193) The presentinvention relates to a printing hammer arrangement for a line printer,and more particularly to printing apparatus in which printing hammerscooperate with a type carrier, such as a type barrel or type rod toprint one line of characters,'while a complete set of types passes at aprinting station.

It is known to select the printing hammers by electromagnetic means, andto move the printing hammers to a printing position by mechanical drivemeans, such as a toothed drive roll.

It is one object of the invention to improve known printing hammerarrangements for line printers, and to provide a very rapidly operatingline printer, comprising only a few movable parts.

Another object of the invention is to provide a printing hammerarrangement in which the printing hammer will move only once to theprinting position, and cannot be actuated a second time if theelectromagnetic means is still energized when the printing hammerreturns to its position of rest.

Another object of the invention is to provide a printing hammerarrangement in which the printing hammers are not subjected to a hardblow by the toothed drive wheel.

Another object of the invention is to provide a printing hammerarrangement in which the printing hammers are angularly movable wheninoperative, but are reliably guided to a printing position.

Another object of the invention is to provide a quietly operatingprinting hammer arrangement.

With these objects in view, the present invention relates to a printinghammer arrangement for a line printer in which the printing hammerscooperate with a type carrier. One embodiment of the invention comprisesa printing hammer cooperating with the type carrier; supporting meanssupporting the printing hammer for movement between an inoperativeposition and a printing position, and also for movement in theinoperative position between a position of rest and an actuatedposition; actuating means, preferably electromagnetic means, for movingthe printing hammer from the position of rest to the actuated position;drive means, preferably a toothed drive roll engaging the printinghammer in the actuated position and moving the same to the printingposition; and restoring means, preferably two springs acting intransverse directions, for returning the printing hammer from theprinting position to the position of rest.

The electromagnetic actuating means includes an armature serving asselector member and acting on a thin wire to bend the same to a positionengaging the printing hammer so that the same is moved from the positionof rest to the actuated position in which it is engaged by the tootheddrive roll. One spring of the restoring means urges the printing hammerto return from the printing position to the inoperative position, andanother spring of the restoring means urges the printing hammer in asecond transverse direction to return the printing hammer from theactuated position to the position of rest. The second spring ispreferably a leaf spring, and moves the printing hammer away from thedrive roll as soon as the printing hammer separates from the drive roll.

In the preferred embodiment of the invention, the printing hammer has anelongated transverse projection engaged by the toothed drive roll, andthis projection is slightly resilient so. that no hard blow is exertedby the drive roll on the printing hammer, and the acceleration of theprinting hammer is gradual. As compared with known constructions inwhich resilient teeth are provided on the drive roll, the constructionof the invention has the advantage that a fewer number of resilientparts is required. Furthermore, a broken projection on a printing hammeris easily repaired by replacing the printing hammer, while repair of theprinting roll when a tooth of the same breaks is expensive anddifficult.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. la is a fragmentary schematic side elevation, partially in section,and illustrating one embodiment of the invention in a position of rest;

FIG. 1b is an elevation corresponding to FIG. 1a' but illustrating thedevice in an actuated position;

FIG. 10 is an elevation corresponding to FIGS. 1a and 1b, andillustrating the device in the printing position; and

FIG. 1d is an elevation corresponding to FIGS. 1a to la and illustratingthe device in another operational position.

Referring now to the drawings, a rotary type carrier 1 is driven in theusual manner to rotate in the direction of the arrow to move types onthe periphery thereof successively into and out of a printing area inwhich a line portion of a paper web 8 is located. A row of printinghammers 2, of which only one is visible in the drawing, cooperates withthe type carrier 1 to press the paper web in the printing position shownin FIG. 10 against the respective type.

The forward ends of the printing hammers 2 are guided between a pair ofguide members 3, 4, which are cylindrical so that the printing hammerscan individually turn between the position of rest shown in FIG. 1a, andthe actuated position shown in FIG. lb in which an elongated transversecoupling projection 22 projects into a recess between the peripheralteeth of a drive roll 21. In the position shown in FIG. la, a first stop5 stops movement of the printing hammer in a position of rest, and asecond stop 7 stops movement of the printing hammer in the actuatedposition shown in FIG. 1b.

In the positions shown in FIGS. 1a and 1b, the printing hammer isinoperative and spaced from the type carrier 1, but due to the rotationof power roll 21, a printing hammer in the actuated position of FIG. 1bis driven toward the type carrier 1, and during such movement theprinting hammer is guided by the pair of guiding members 3, 4 so thatthe paper web 8 is accurately pressed against a type face of typecarrier 1.

A spring 9 is secured to a projection of each printing hammer 2 andurges the same to move from the printing position to the position ofrest in which the rear end of the printing hammer abuts an elasticdamping cushion 11 which is mounted in a stationary support 10. A leafspring 16 is also secured to support 10 and has a portion resilientlyengaging the rear end portions of the printing hammers in theinoperative and printing positions and urging all hammers to move out ofengagement with the teeth of drive roll 21 until stopped by stop 5.During movement of a printing hammer to the printing position, the rearend portion of the printing hammer slides on leaf spring 16. Duringmovement of a printing hammer in 3 the opposite direction, the printinghammer slides on stop 5 and leaf spring 16.

Support carries a pair of holding members 12 and 13, and a comb-shapedleaf spring 14. A series of spring wires is mounted between holdingmembers 12 and 13 and each spring wire 15 has a curved rear end portionbent about hold-ing member 13 and pressed against the same by leafspring 14. The forward end of each spring wire 15 has a transverselybent end portion projecting toward the corresponding printing hammer 2above and spaced from the rear end of the same.

Each printing hammer 2 and spring wire 15 is associated with anelectromagnetic selector means including a core and winding 17, and amovable armature mounted on a pivot 19 on support 10 and having aselector portion 18 which is urged by the respective spring wire 15 intoabutment with a fixed stop 20. When an electromagnetic means 17 'isenergized, the armature is attracted, and selector member 18 bends thespring wire 15 to the position shown in FIG. 1b in which the spring wireabuts a fixed stop 12 on support 16. At the same time, the bent-over endportion of the spring wire engages rear end of the printing hammer andmoves then the same from the position of rest toward the actuatedposition shown in FIG. 1b in which leaf spring 16 abuts stop 7. At thesame time, the elongated projecting portion 22 of the respectiveprinting hammer 2 moves into a recess between adjacent peripheral teethof drive roll 21, which is driven in synchronism with the type carrier1.

Since the pitch of the teeth of the drive roll 21 corresponds to thepitch of the types on type carrier 1, any angular movement of the driveroll 21 over an angle corresponding to the angular spacing of two teeth,re sults also in angular displacement of the type carrier for the angleat which two types are spaced.

The series of electromagnetic means 17, 18 is controlled by impulseswhich arrive at timed intervals corresponding to the position of thetypes of the type carrier, but within the time period corresponding toone revolution of the type carrier, so that each electromagnetic means17, 18 is energized when selected and desired type moves into theprinting area associated with the respective printing hammer, so that anentire line is printed of different characters during one revolution ofthe printing type carrier.

At the beginning of the operation, all printing hammers 2 are in theposition of rest shown in FIG. 1a in which the printing hammers abutstop 5 under the action of leaf spring 16, and abut the resilientcushion 11 under the action of spring 16. The elongated projection 22 islocated spaced from drive roll 21, and the forward end portion of eachspring wire 15 is located spaced a small distance above the rear end ofthe respective printing hammer which is possible since electromagneticmeans 17 is not energized.

When an electromagnetic means 17 is energized by a command impulse, therespective selector member 18 is turned in counterclockwise direction sothat the respective spring wire is bent to assume the position shown inFIG. lb whereby selector member 18 is coupled with the respectiveprinting hammer 2 and turns the same in clockwise direction whilebending the spring 16 until the same abuts stop 7.

The printing hammer 2 is still inoperative, but has been moved by theactuating means 17, 18, 15 to an actuated position in which itselongated projection is located in a recess between a pair of teeth ofdrive roll 21 so that the printing hammer is driven toward the left outof the inoperative position shown in FIGS. la and 1b toward the printingposition shown in FIG. 1c. Guide members 3 and 4 permit the angularmovement of the printing hammer from the position of rest of FIG. la tothe actuated position of FIG. lb, but guide the printing hammer :duringmovement to the printing position, and assure that the forward end ofthe printing hammer cooperates precisely with a type face of the typecarrier 1 located in the printing area.

During the movement of the printing hammer toward the printing position,projection 22 is released by the respective drive tooth of power roll21, so that the printing hammer is no longer connected with drive wheel21 when arriving in the printing position of FIG. 1c. Spring 16 urgesthe printing hammer to turn in counterclockwise direction for movingprojection 22 away from the power roll 21. Each printing hammer 2 has aprojection 2' with a slanted camming face located in the region of astationary guide 6, but spaced from the same in the position of rest ofthe printing hammer. In the actuated but inoperative position of theprinting hammer shown in FIG. lb, the forward end of the camming face islocated in the proximity of guide 6. When drive roll 21 drives theprinting hammer toward the printing position, guide 6 acts on theslanted camming face of projection 2 to turn the printing member out ofthe actuated position connected with the drive roll to the positionshown in FIG. 10 in which the printing hammer abuts stop 5 under theaction of spring 16 which participates in angularly displacing printinghammer 2 out of the actuated position shown in FIG. lb.

Since printing hammer 2 already abuts stop 5 before arriving in theprinting position, printing hammer 2 moves perpendicularly to theperiphery of the type carrier 1 during the last part of its stroketoward the printing position so that the end face of the printing hammeris parallel to the paper web 8. The position of stop 5 and the slantedcamming face of projection 2 may be so designed that the type carrier 1takes along the forward end portion of the printing hammer 2 in theprinting position to turn the printing hammer a very small angle untilit abuts stop 5. Such extremely short movement of the printing hammerwith the rotating type carrier produces a particularly clear imprintsince the type and the end face of the printing hammer move at the samespeed during the short time in which the imprint is being made.

Directly after the imprint spring 9 retracts the printing hammer whichslides along leaf spring 16 and stop 5 toward the inoperative position.It is immaterial whether electromagnetic means 17 is energized or not,since spring 16 holds the printing hammer in a position in which itsprojection 22 cannot be engaged by the teeth of the power roll.

If electromagnetic means 17 is still energized, the transverse endportion of spring wire 15 is located between the rear end face ofprinting hammer 2 and the elastic cushion 11, and as soon as theelectromagnetic means 17 is deenergized, spring wire 15 will raiseselector member 18 and resiliently return to its normal position shownin FIG. la so that spring 9 will pull printing hammer 2 to its positionof rest abutting cushion 11 as shown in FIG. la.

If the electromagnetic means 17 is deenergized when the printing hammeris returned by spring 9, the rear end face of the printing hammer willimmediately abut elastic cushion 11.

The cushion 11 serves as clamping member to avoid dangerous reboundingof hammer 2. The projection 22 is comparatively long so as to besomewhat resilient so that projection 22 resiliently yields under theimpact of the respective drive tooth of drive roll 21, resulting in amore gradual acceleration and in a quiet operation.

From the above description it will be apparent that guiding members 3,4, stops 5, and 7, support 10 and cushion 11, constitute supportingmeans permitting the printing hammer to move between the inoperativeposition shown in FIGS. la, 1b, 1d, and the printing position shown inFIG. 10, and also permit the printing hammer to angularly move inanother direction between the position of rest shown in FIG. la and theactuated position shown in FIG. 1b. Electromagnetic means 17 withselector member 18 and spring wire 15 constitute actuating means formoving the printing hammer from the position of rest to the actuatedposition and the spring wire 15 serves as resilient coupling memberbetween selector member 18 and printing hammer 2.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofprinting hammer arrangements differing from the types described above.

While the invention has been illustrated and described as embodied inprinting hammers which are angularly turnable to and from an actuatedposition cooperating with a drive means, it is not intended to belimited to the details shown since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Printing hammer arrangement for a line printer comprising, incombination, type carrier means movable for placing types successivelyin a printing area; a printing hammer cooperating with said type carriermeans; supporting means including a pair of guide members located onopposite sides of said printing hammer for supporting the same forforward movement between an inoperative position and a printing positionin which a part thereof is located in said printing area, and also forturning movement in said inoperative position between a position of restand an actuated position; first and second stop means for stopping saidturning movement of said printing hammer in said position of rest andsaid actuated position, respectively; actuating means. for turning saidprinting hammer from said position of rest to said actuated position;drive means engaging said printing hammer in said actuated position formoving the same forward to said printing position; and restoring meansfor returning said printing hammer from said printing position to saidposition of rest.

2. A printing hammer arrangement according to claim 1 wherein said drivemeans includes a rotary drive roll having drive teeth; and wherein saidprinting hammer has an elongated projection projecting toward said driveroll spaced from the same in said position of rest, and being engaged bya drive tooth of said drive roll in said actuated position so that saidprinting hammer is driven toward said printing position, said projectionbeing constructed to provide an elastic connection between said driveroll and said printing hammer.

3. A printing hammer arrangement according to claim 1 wherein saidsupporting means includes an elastic abutment engaged by said printinghammer in said inoperative position when returned from said printingposition by said restoring means.

4. A printing hammer arrangement according to claim 1 wherein saidrestoring means include a first spring for urging said printing hammerfrom said printing position to said inoperative position, and a secondspring stressed by said printing hammer in said actuated position andurging said printing hammer out of engagement with said drive means.

5. A printing hammer arrangement according to claim 1 wherein saidrestoring means include a first spring for urging said printing hammerto said inoperative position, and a second leaf spring for urging saidprinting hammer out of engagement with said drive means and toward saidfirst stop whereby said printing hammer engages said first stop in saidprinting position and slides onthe same and on said leaf spring whilebeing returned toward said position of rest by said first spring.

6. A printing hammer arrangement according to claim 1 wherein saidprinting hammer has a projection with a slanted camming face; andincluding a stationary guide engaged by said slanted camming face duringmovement of said printing hammer in said actuated position toward saidprinting position so that said guide and said slanted camming face movesaid printing hammer out of said actuated position whereby said printinghammer is disengaged from said drive means before arriving in saidprinting position.

7. A printing hammer arrangement according to claim 6 wherein saidactuating means include electromagnetic means having a movable selectormember; and including a thin resilient coupling member 'between saidselector member and said printing hammer and engaged and bent by saidselector member when said electromagnetic means is actuated, said bentresilient coupling member engaging said printing hammer in said positionof rest and moving the same to said actuated position for engagement bysaid drive means.

8. A printing hammer arrangement according to claim 1 and including cammeans for moving said printing hammer out of engagement with said drivemeans during movement of said printing hammer toward said printingposition.

References Cited by the Examiner UNITED STATES PATENTS 9/1935 Buhler"101-93

1. PRINTING HAMMER ARRANGEMENT FOR A LINE PRINTER COMPRISING, INCOMBINATION, TYPE CARRIER MEANS MOVABLE FOR PLACING TYPES SUCCESSIVELYIN A PRINTING AREA; A PRINTING HAMMER COOPERATING WITH SAID TYPE CARRIERMEANS; SUPPORTING MEANS INCLUDING A PAIR OF GUIDE MEMBERS LOCATED ONOPPOSITE SIDES OF SAID PRINTING HAMMER FOR SUPPORTING THE SAME FORFORWARD MOVEMENT BETWEEN AN INOPERATIVE POSITION AND A PRINTING POSITIONIN WHICH A PART THEREOF IS LOCATED IN SAID PRINTING AREA, AND ALSO FORTURNING MOVEMENT IN SAID INOPERATIVE POSITION BETWEEN A POSITION OF RESTAND AN ACTUATED POSITION; FIRST AND SECOND STOP MEANS FOR STOPPING SAIDTURNING MOVEMENT OF SAID PRINTING HAMMER IN SAID POSITION OF REST ANDSAID ACTUATED POSITION, RESPECTIVELY; ACTUATING MEANS FOR TURNING SAIDPRINTING HAMMER FROM SAID POSITION OF REST TO SAID ACTUATED POSITION;DRIVE MEANS ENGAGING SAID PRINTING HAMMER IN SAID ACTUATED POSITION FORMOVING THE SAME FORWARD TO SAID PRINTING POSITION; AND RESTORING MEANSFOR RETURNING SAID PRINTING HAMMER FROM SAID PRINTING POSITION TO SAIDPOSITION OF REST.